This invention relates to an improved device for the continuous-flow treatment of textile material, fleeces or paper with a gaseous or liquid treatment medium circulated in the device having a permeable sheet-metal drum as a transport member, said drum being under suction and having bases on its ends, and its perimeter or peripheral surface covered with a screen-type layer, and between the screen-type layer and the perimeter of the drum, as a support or girder means to increase the distance between the drum body and the screen-type layer, there are disposed parallel over the whole length of the drum from base to base straight sheet-metal strips, the sheet-metal drum fitting directly against the radially inwardly-situated edges of the metal strips, and these metal strips being closely connected with the outer perimeter of the sheet-metal drum body. A device having such an arrangement is disclosed in German application P 44 22 508.3 and corresponding U.S. application Ser. No. 08/493,321.
The particular advantages of a screen drum construction in which a girder construction known from DE 38 05 738 A1, in a drum sheet-metal casing construction, is replaced by upright sheet-metal strips which extend parallel over the whole length of the drum unbent from one end of the drum to the other, is an inexpensive drum construction with extremely high air permeability in the region of the textile material lying on it, although the sheet-metal drum support structure which is not so permeable and it in itself an obstacle, remains unchanged. These metal strips serve only to increase the distance of the screen cloth from the sheet-metal casing and increase the distance between the screen drum and the screen cloth in such a way, that the lesser air permeability of the perforated drum is not a significant factor. In this construction the increase in resistance of the screen drum to denting is also important.
Sheet-metal strips extending in a two-dimensional plane can only be attached to the screen drum by welding. But not only does the welding process result in structural changes in the metal, but the welding seams can also in the long run tear under extreme thermal stress, for instance, through constant temperature changes to the screen drum as when cold and wet material come in as opposed to the dry and hot material which has just left. Expensive repairs are then necessary.